docstr: Initialise online state (the stateful attributes updated by `score` and `predict`). This method relies on
  attributes defined by `_configure_ref_subset`, hence must be called afterwards.
docstr_tok: ["Initialise","online","state","(","the","stateful","attributes","updated","by","`","score","`","and","`","predict","`",")",".","This","method","relies","on","attributes","defined","by","`","_configure_ref_subset","`",",","hence","must","be","called","afterwards","."]
code: def _initialise_state(self) -> None:
      """
      Initialise online state (the stateful attributes updated by `score` and `predict`). This method relies on
      attributes defined by `_configure_ref_subset`, hence must be called afterwards.
      """
      super()._initialise_state()
      self.test_window = self.x_ref[self.init_test_inds]
      self.k_xy = self.kernel(
          self.x_ref[self.ref_inds], self.test_window
      )
  
file_path: alibi-detect/alibi_detect/cd/pytorch/mmd_online.py
imports: from tqdm import tqdm
  import numpy
  import torch
  from typing import Any, Callable, Optional, Union
  from alibi_detect.cd.base_online import BaseMultiDriftOnline
  from alibi_detect.utils.pytorch import get_device
  from alibi_detect.utils.pytorch.kernels import GaussianRBF
  from alibi_detect.utils.pytorch import zero_diag, quantile
  from alibi_detect.utils.frameworks import Framework
  from alibi_detect.utils._types import TorchDeviceType
label_desc: Use image node_id 2 for calling the MMDDriftOnlineTorch obj's underlying member method code with example usage: obj._initialise_state() without return types